DRY-FARMING 



nights. Thus it is that in some parts of 

 the United States, notably California, 

 summer fogs have a markedly good effect 

 upon vegetation. And although this 

 moisture is of but little value save in 

 times of severe drought, it is not to be 

 despised by any means. During the hot 

 days of summer a soil of a high ab- 

 sorptive power such as a well-tilled clay 

 loam, will retain its moisture for a much 

 longer time than a soil of low absorptive 

 power, such as a shallow sandy soil, 

 whose store of moisture will be exhausted 

 in a few hours, while the surface of the 

 land itself is heated up to the scalding 

 point, thereby searing the stems and 

 root-crowns of the growing crop. It is 

 also worthy of note that, generally speak- 

 ing, soils of high absorptive power are 

 also those of high capillary power. 



Hilgard summarizes the effect of hy- 

 groscopic moisture as follows : 

 80 



